1. Field of the Invention
The present invention relates to a catheter and in particular to a catheter having a nonreturn valve which inhibits penetration of fluid and which opens in case of internal overpressure.
2. Description of Related Art
A catheter including a nonreturn valve is known (European Patent No. 0 018 179) which comprises a flexible tubular sleeve laterally surrounding the catheter head. The end of the catheter lumen is firmly closed by a plug which is anchored by a lateral adapter in a hole of the catheter tube. The flexible sleeve covers lateral holes of the catheter tubing. In case of overpressure in the catheter lumen, the flexible sleeve is partly lifted from the hose so that fluid may flow from the interior of the catheter tubing through the enlarged flexible sleeve to the outside. Due to the sealing effect of the sleeve which flexibly adjoins the catheter tubing, fluid is prevented from entering into the catheter head.
The production of such a nonreturn valve is expensive because, for closing the catheter end, a separate member is required which, with respect to the catheter tubing, has to act as a seal, and because radial openings must be provided at the catheter tube. Because of the use of cooperating flexible elements, namely the catheter tubing and the sleeve, the required sealing and opening behavior of the valve may be achieved only with difficulty. Further, during the assembly of the valve, it is difficult to slip the flexible sleeve over the catheter tubing, which is itself flexible.
It is therefore an object of the present invention to provide a catheter having a nonreturn valve which may be simply produced and in which the nonreturn valve has a reproducible, well-defined behavior in operation.